The present invention relates to boat control systems. In particular, the invention relates to control of trim tabs and trolling motors mounted to the transom of a boat.
Trim tabs are plates that are mounted on the lower transom of a boat. Typically, at least one trim tab is pivotally mounted on the left or port side and at least one trim tab is pivotally mounted on the right or starboard side of the transom. In other cases, a single center-mounted trim tab can be used. The trim tabs are raised and lowered by a drive mechanism. Early trim tab systems used mechanical jackscrews to raise and lower the trim tabs. Currently available systems use either hydraulic or electromechanical actuators to raise and lower the trim tabs.
Trim tabs are used to provide additional boat control for reasons such as uneven load distribution in the boat, controlling bow attitude in various water conditions, and trimming the boat out of the water faster in conditions such as shallow water operations. Depending on the type of boat and the number and position of occupants, the attitude (or side-to-side angle along the keel) can tilt left or right. Trim tabs can improve boat performance by leveling the boat. Trim tabs also can be used to increase top end speed, to improve “hole-shot”, and to provide a dryer ride by keeping the nose down and the boat up on plane.
Fishing boats are often equipped with a trolling motor that provides a relatively small amount of thrust to slowly and quietly propel the boat while the operator is fishing. The electric trolling motor is powered by a battery or batteries, and is mounted to either the bow or the stern of the boat. The trolling motor is raised out of the water when not in use and when the boat is being driven at high speed by the main engine.
Electric trolling motors have also been mounted on trim tabs, as shown in U.S. Pat. Nos. 5,704,308; 5,878,686; and 6,863,581 by Anderson and in U.S. Pat. Nos. 5,842,895, and 6,520,813 by DeVito, Jr. When the trim tabs are performing a trimming function, the trolling motors are elevated so they are out of the water. When trolling is required, the position of the trim tabs is adjusted so that the trolling motor is below the surface of the water and can provide thrust to move the boat. Steering with the trim tab mounted trolling motors is accomplished by adjusting the relative speeds and propeller directions of the motors mounted on the left and right trim tabs.
This type of propulsion can offer a number of benefits to anglers. First, trim tab mounted trolling motors provide an alternative to either a bow mounted or a transom mounted trolling motor. The trim tab mounted trolling motors keep the lines of the boat cleaner, and provide less obstruction to the angler while fishing from various locations within the boat.
Second, the trolling motors allow the boat to run in very shallow water. The trim tabs can position the electric trolling motors just below the surface of the water.
Third, a pair of electric trolling motors mounted on trim tabs at the back of the boat can deliver twice the thrust of a single trolling motor with a traditional transom mount, or a single trolling motor with a bow mount.